WASHINGTON >> If Donald Trump wants to know whether he was the subject of surveillance by the U.S. government, he may be uniquely positioned to get an answer.

A series of weekend tweets by the president focused public attention on intelligence collection efforts long shrouded in secrecy. He accused former President Barack Obama of ordering wiretaps on his phones but offered no proof to back the claim, and the White House then called on Congress to investigate the allegations.

But former government lawyers say Trump hardly needs Congress to answer this question.

“The intelligence community works for the president, so if a president wanted to know whether surveillance had been conducted on a particular target, all he’d have to do is ask,” said Todd Hinnen, head of the Justice Department’s National Security Division during the Obama administration and a National Security Council staff member under George W. Bush.

The latest storm began Saturday when Trump tweeted: “Is it legal for a sitting President to be ‘wire tapping’ a race for president prior to an election? Turned down by court earlier. A NEW LOW!” He followed up with: “How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!”

The Justice Department, not the president, would have the authority to conduct such surveillance, and officials have not confirmed any such action. Through a spokesman, Obama said neither he nor any White House official had ever ordered surveillance on any U.S. citizen. Obama’s top intelligence official, James Clapper, also said Trump’s claims were false, and a U.S. official told The Associated Press that the FBI asked the Justice Department to rebut Trump’s assertions.

Why turn to Congress, Trump spokesman Sean Spicer was asked today.

“My understanding is that the president directing the Department of Justice to do something with respect to an investigation that may or may not occur with evidence may be seen as trying to interfere,” Spicer said. “And I think that we’re trying to do this in the proper way.”

He indicated that Trump was responding to media reports rather than any word from the intelligence community. Other officials have suggested the president was acting on other information.

Sen. John McCain, chairman of the Armed Services Committee, said today that Trump needs to give more information to the American people and Congress about his wiretapping accusations. “The dimensions of this are huge,” McCain said. “It’s accusing a former president of the United States of violating the law. That’s never happened before.”

As for the genesis of a possible wiretap, it is possible the president was referring to the Foreign Intelligence Surveillance Act, a 1978 law that permits investigators, with a warrant, to collect the communications of someone they suspect of being an agent of a foreign power. That can include foreign ambassadors or other foreign officials who operate in the U.S. whose communications are recorded for counterintelligence purposes as a matter of routine.

The government’s use of that act is secret, the warrant application process classified. But, as president, Trump has the authority to declassify anything. And were such a warrant to exist, he could theoretically make it public as well.

If the president demands to know what happened, “the Justice Department can decide what’s appropriate to share and what’s not,” said Amy Jeffress, another former Obama administration national security lawyer.

The Justice Department applies for the warrants in a one-sided process before judges of the secretive Foreign Intelligence Surveillance Court. Permission is granted if a judge agrees that there’s probable cause that the target is an agent of a foreign power. Though the standard seems a high bar to meet, applications are hardly ever denied.

Targets of wiretaps are not alerted that their communications are being recorded. Defendants later charged in the criminal justice system may ultimately learn that the government intends to use at trial evidence collected through a FISA warrant, but they are not presented with the actual application for a warrant. And FISA warrants have never been publicly disclosed.

“Unfortunately, the public has never seen an actual FISA application over nearly 40 years, so we don’t know exactly how the FISA Court has applied or interpreted the probable cause standard in this context,” said Patrick Toomey, an American Civil Liberties Union staff attorney specializing in national security.

Trump also could have been referring to wiretapping authorized under the Omnibus Crime Control and Safe Streets Act of 1968. The Justice Department can obtaining a warrant for that surveillance by convincing a judge that there’s probable cause to believe the target has committed or is in the process of committing a crime.

The White House turned Sunday to Congress — which is already investigating ties between Trump associates and Russians — for help finding evidence to support his assertions. Some Republicans seemed inclined to try to help Trump get answers.

For Congress, getting to the bottom of this should not be difficult, said Dan Jones, a former Senate investigator and currently president of the Penn Quarter Research and Investigations Group.

“It’s a knowable, ‘yes or no,’” Jones said. If the answer is there was no such warrant, he said, the next step would be to ask the president why he made the claim. “That information would then be investigated to find out if it’s right or wrong.”